Low-tension ignition system fob



Nov. 9, 1948. M, P. MCKAY 2,453,636

Low TENSION IGNITION SYSTEM FOR MINIATURE TWO-CYCLE GAS ENGINES Filed Oct 31 1944 2 Sheets-Sheet 1 m all. 1 0 6 in 4 Nov. 9, 1948. p Mc 2,453,636

LOW TENSION IGNITION SY TE FOR MINIATURE TWO-CYCLE GAS ENG NES 2 Sheets-Sheet 2 Filed Oct. 31, 1944 TIImmEIU Patented Nov. 9, 1948 UNITED sures PATENT OFFICE LOW-TENSION IGNITION SYSTEM FOR MINIATURE TWO-CYCLE GAS ENGINES Maurice P. McKay, Trontdale, Oreg.

Application October 31, 1944, Serial No. 561,239

4 Claims.

This invention relates to a low tension ignition system for two-cycle gas engines, the same being especially, but not necessarily, applicable to miniature two-cycle engines of the types used in model airplanes and the like.

My primary aim is to generally improve upon ignition systems in the category stated, whereby to make it possible to construct a reliable gas engine which, it is believed, can be manufactured as cheaply as the conventional type, while at the same time simplifying and lessening the upkeep and necessary repairs to the ignition system itself.

One phase of the invention has to do with a simple and practicable twin-coil magneto, this being mounted directly on the crankcase and wired to the coacting sparkplug and grounded on said crankcase, said magneto embodying complemental cores projecting into the interior of the crankcase for coaction with a permanent magnet on the rotatable crank shaft.

Another improvement resides, it is submitted, in the adoption and use of a crank arm carried by the crank shaft, this for association with the projecting cores carried by said magneto, said arm serving in its usual capacity as a crank and counterbalance and having the additional function of a permanent magnet. I

The other and remaining phase of the invention has to do with the'make and break assemblage mounted in the cylinder in the combustion space, this comprising a yieldably supported adapted arm with a contact button coacting with the electrode of the spark plug, the free end of said adapter coacting with a flexible trip carried by the adjacent upper end of the reciprocating piston, the parts being constructed and arranged to permit the desired'sequence of operation.

Other features and advantages will become more readily apparent from the following description and the accompanying illustrative draw- 8s.

In the drawings, wherein like numerals are employed to designate like parts throughout the same:

Figure 1 is a view partly in section and partly in elevation, the sectional phases representing the motor block and the parts in elevation depicting the improved low tension ignition system and parts of the engine directly associated therewith.

Figure 2 is an enlarged end elevation of the crank shaft and crank arm thereon showing the specific construction of said crank arm.

and a low tension spark plug at 2. The crankcase, attached to the lower end of the cylinder,

is denoted generally by the reference character 3. The piston 4 is conventional and provided with the customary connecting rod or pitman 5, this connected to the crank arm 6 carried by the rotary crank shaft '1 journaled in a bearing in the crankcase. This crank arm is believed to be new and that it has several functions. It serves, first, as the crank proper, and its lower end is weighted, as at Go to serve as a counterbalance. The entire arm is of suitable steel magnetized of the type of metal used for permanent magnets.

As previously indicated, the diametrically opposite cores 8, of suitable construction, are mounted in adapter bores fitted in the crankcase as shown to the right in Figure 1. These cores are electrically associated with the spool-like coils III also diametrically arranged and supported on an assembling ring 9 surrounding the protruding bearing. The coils are interconnected, as at Ila (see Fig. 3), one of said coils bein grounded, as at H, on the crankcase. The remaining or top coil is provided with a conductor l2 which extends up to and is electrically connected with the spark plug 2.

I next call attention to the spring trip finger I3 of suitable shape (see Fig. 5), this being mounted on an appropriate lug IS. The free end of the trip 13 is adapted to coact with the downbent end I 6 on the make-and-break adapter, the latter being carried by a suitably riveted and fastened fixture H (see Fig. 4). The intermediate portion of the flexible adapter arm I6 is provided with a contact button I8 coacting with the adjacent lower end of the spark plug electrode I It is evident that the system has two'main phases or parts, the low tension magneto composed of the frame 9, coils I0 and cores -8 with the cores coacting with the magnet 6. The second phase has to do with the circuit make and break arrangement in the combustion chamber the contact button l8 and to coact with the free wire cores and their magnetically linking connection, thus inducing an alternating current in the coils of one cycle per revolution of the crank shaft. This one magneto could be used on a two-cylinder motor similar to that drawn by merely tying two ignition plugs together electrically, as the points in one cylinder would be open and would not interfere, at the time, with the other one sparked. This low tension magneto could be used to replace the dry cells in a high tension system on this type of engine. The iron cores and coils are constructed on the crankcase so that the permanent magnet is opposite them at the time the ignition spark is desired.

@n the up stroke of the piston, the spring finger i3 pushes against the adapter element to until the points ill and i8 close. Further upward motion or the piston causes the finger to bend, releasing the coacting parts and allowing the points to snap open as desired in make and break ignition. This occurs ahead of dead. center and may be regulated by the thickness of the spark plug gasket or the addition of shims where needed.

In Figure l, the exhaust port 2!] is in about the correct spot and proportion and is uncovered at the lower end of each stroke to allow exhaust gases to escape. The intare port 2a is almost simvltaneouslyuncovered hy the piston which connects through a passage 59 to the crankcase which allows the gases compressed in the crank case to pass into the cylinder. Projection serves also as a baffle to prevent said gases from passing on out the exhaust port for the most part. The upper end of the bypass should he enough (in Fig. l), relatively, so that it will he uncovered during the low part of the stroke, while the lower end of the bypass should at that time communicate with the crankcase.

Obviously, with reference to. the passages or ports i9, 28, and 20, these are purely incidental and form no part of the instant invention.

Referring again to lug i5, it is to be mentioned this performs the conventional function. of a piston i tie to the rnhzttue of burnt and teases.

Zin once again to o illustrating the cor ea-lied horseshoe or U=sha ed elmtroanagnet, might he added, by way clarification, this comists of a loar magnet rotating in held of a horseshoe electro rnagnet.

A careful consideration of the foregoing description in conjunction with the invention as illustrated in the drawings will enable the reader to obtain a clear understanding and impression of the alleged features of merit and novelty sufflcient to clarify the construction of the invention as hereinafter claimed.

Minor changes in shape, size, materials and rearrangement of parts may be resorted to in actual practice so long as no departure is made from the invention as claimed.

l3 claim:

i. In a structure of the class described, in combination, a cylinder, a piston slidable therein, a crank shaft mountedior rotation in a bearing, a crank arm on said crank shaft, said crank arm loe= ing in the form of a permanent magnet, an oper= ating connection between the piston and crank arm, a pair of coils mounted on the exterior or the cylinder and having associated cores project- ,ing into operating association with said crank 2. In a structure of the class described, a cylinder, 9, crankcase carried by said cylinder, a piston reciprocating in said cylinder and provided with a connecting rod, a crank shaft mounted in said crankcase and provided with an arm located in the crankcase, an operating connection between the arm and connecting rod, cores mounted in said crankcase having their inner ends projecting into association with said arm, said arm being in the form of a permanent magnet, coils on the exterior of the crankcase connected with said cores.

3. In a low tension ignition system tor twocycle gas engines, a cylinder block embodying a cylinder, a piston mounted for reciprocation in said cylinder, a crankcase having a bearing, a crank shaft mounted for rotation in said bearing, a crank arm on the inner end of said crank shaft and operable in said crankcase, a connecting rod carried by said piston and connected with said crank arm, said crank arm being composed of magnetized steel and constituting a rotary permanent magnet, a frame on the exterior of said crankcase, a pair of diametrically opposite coils mounted on said frame, said coils being electricah ly connected together, one of said coils bein grounded on the crankcase, and cores carried bl] said coils and mounted in bores in said crankcase, the inner ends of said cores being diametrically arranged and coasting with end portions of the crank arm swingable in a circular path in rela tion to the protruding ends of said cores.

4. In combination, a crankcase having a cylln der mounted thereon, a crankshaft journaled in said crankcase, a crank throw and an oppositely disposed. counterbalance forming a straight line therewith on said crank shaft, a piston in said cylinder operatively connected to said cranit throw, said crank throw and counterbalance forming a bar type of permanent magnet, a pair of cores on tending into said crankcase and diametrically disposed on opposite sides or said cranlr a coil electrically connected to and surrounding the end of each core and positioned exteriorly of said crankcase, the crankpin end of said crank. throw and the counterbalance constituting poles of said permanent P. MICKEY.

The following reierences are of record the file of this patent:

UNITED PATENTS Number Name Date 26,558 Beardslee Dec. 27, M9255 Sinta Nov. 21, 1893 633,275 Riotte Sept. 3.9, 1899 1,275,292 Neuland Aug. 13, 1918 1,321,153 Stark Nov. 11, 1919 1,434,685 Diifendorf Nov. 7, 1922, 1,505,702 Curtis Aug. 19, 1924 1,544,619 Jordan June 30;, 1.925 1,970,327 Louis Aug. 193 i 2,285,463 Rldgway June 9, 1942 2,432,117 Morton Dec. 7, 1947 FOREIGN PATENTS Number Country Date 191,496 Austria Mar. 10, 1905 153,386 Germany July 11, 1904 

